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- All Subjects: Chemistry
- Creators: School of International Letters and Cultures
- Creators: Ros, Alexandra
- Resource Type: Text
Description
Bioanalytes such as protein, cells, and viruses provide vital information but are inherently challenging to measure with selective and sensitive detection. Gradient separation technologies can provide solutions to these challenges by enabling the selective isolation and pre-concentration of bioanalytes for improved detection and monitoring. Some fundamental aspects of two of these techniques, isoelectric focusing and dielectrophoresis, are examined and novel developments are presented. A reproducible and automatable method for coupling capillary isoelectric focusing (cIEF) and matrix assisted laser desorption/ionization mass spectrometry (MALDI-MS) based on syringe pump mobilization is found. Results show high resolution is maintained during mobilization and &beta-lactoglobulin; protein isoforms differing by two amino acids are resolved. Subsequently, the instrumental advantages of this approach are utilized to clarify the microheterogeneity of serum amyloid P component. Comprehensive, quantitative results support a relatively uniform glycoprotein model, contrary to inconsistent and equivocal observations in several gel isoelectric focusing studies. Fundamental studies of MALDI-MS on novel superhydrophobic substrates yield unique insights towards an optimal interface between cIEF and MALDI-MS. Finally, the fundamentals of isoelectric focusing in an open drop are explored. Findings suggest this could be a robust sample preparation technique for droplet-based microfluidic systems. Fundamental advancements in dielectrophoresis are also presented. Microfluidic channels for dielectrophoretic mobility characterization are designed which enable particle standardization, new insights to be deduced, and future devices to be intelligently designed. Dielectrophoretic mobilities are obtained for 1 µm polystyrene particles and red blood cells under select conditions. Employing velocimetry techniques allows models of particle motion to be improved which in turn improves the experimental methodology. Together this work contributes a quantitative framework which improves dielectrophoretic particle separation and analysis.
ContributorsWeiss, Noah Graham (Author) / Hayes, Mark A. (Thesis advisor) / Garcia, Antonio (Committee member) / Ros, Alexandra (Committee member) / Arizona State University (Publisher)
Created2011
Description
Water-soluble, adenosine triphosphate (ATP)-stabilized palladium nanoparticles have been synthesized by reduction of palladium salt in the presence of excess ATP. They have been characterized by electron microscopy, energy dispersive X-ray spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and X-ray diffraction in order to determine particle size, shape, composition and crystal structure. The particles were then subsequently attached to a glassy carbon electrode (GCE) in order to explore their electrochemical properties with regard to hydrogen insertion in 1 M sodium hydroxide. The particles were found to be in the size range 2.5 to 4 nm with good size dispersion. The ATP capping ligand allowed the particles to be air-stable and re-dissolved without agglomeration. It was found that the NPs could be firmly attached to the working electrode via cycling the voltage repeatedly in a NP/phosphate solution. Further electrochemical experiments were conducted to investigate the adsorption and absorption of hydrogen in the NPs in 1 M sodium hydroxide. Results for cyclic voltammetry experiments were consistent with those for nanostructured and thin-film palladium in basic solution. Absorbed hydrogen content was analyzed as a function of potential. The maximum hydrogen:Pd ratio was found to be ~0.7, close the theoretical maximum value for β phase palladium hydride.
ContributorsLamb, Timothy (Author) / Buttry, Daniel A (Thesis advisor) / Yarger, Jeffery (Committee member) / Ros, Alexandra (Committee member) / Arizona State University (Publisher)
Created2013
Description
Complex samples, such as those from biological sources, contain valuable information indicative of the state of human health. These samples, though incredibly valuable, are difficult to analyze. Separation science is often used as the first step when studying these samples. Electrophoretic exclusion is a novel separations technique that differentiates species in bulk solution. Due to its ability to isolate species in bulk solution, it is uniquely suited to array-based separations for complex sample analysis. This work provides proof of principle experimental results and resolving capabilities of the novel technique. Electrophoretic exclusion is demonstrated at a single interface on both benchtop and microscale device designs. The benchtop instrument recorded absorbance measurements in a 365 μL reservoir near a channel entrance. Results demonstrated the successful exclusion of a positively-charged dye, methyl violet, with various durations of applied potential (30 - 60 s). This was the first example of measuring absorbance at the exclusion location. A planar, hybrid glass/PDMS microscale device was also constructed. One set of experiments employed electrophoretic exclusion to isolate small dye molecules (rhodamine 123) in a 250 nL reservoir, while another set isolated particles (modified polystyrene microspheres). Separation of rhodamine 123 from carboxylate-modified polystyrene spheres was also shown. These microscale results demonstrated the first example of the direct observation of exclusion behavior. Furthermore, these results showed that electrophoretic exclusion can be applicable to a wide range of analytes. The theoretical resolving capabilities of electrophoretic exclusion were also developed. Theory indicates that species with electrophoretic mobilities as similar as 10-9 cm2/Vs can be separated using electrophoretic exclusion. These results are comparable to those of capillary electrophoresis, but on a very different format. This format, capable of isolating species in bulk solution, coupled with the resolving capabilities, makes the technique ideal for use in a separations-based array.
ContributorsKenyon, Stacy Marie (Author) / Hayes, Mark A. (Thesis advisor) / Ros, Alexandra (Committee member) / Buttry, Daniel (Committee member) / Arizona State University (Publisher)
Created2012
Description
This work demonstrated a novel microfluidic device based on direct current (DC) insulator based dielectrophoresis (iDEP) for trapping individual mammalian cells in a microfluidic device. The novel device is also applicable for selective trapping of weakly metastatic mammalian breast cancer cells (MCF-7) from mixtures with mammalian Peripheral Blood Mononuclear Cells (PBMC) and highly metastatic mammalian breast cancer cells, MDA-MB-231. The advantage of this approach is the ease of integration of iDEP structures in microfliudic channels using soft lithography, the use of DC electric fields, the addressability of the single cell traps for downstream analysis and the straightforward multiplexing for single cell trapping. These microfluidic devices are targeted for capturing of single cells based on their DEP behavior. The numerical simulations point out the trapping regions in which single cell DEP trapping occurs. This work also demonstrates the cell conductivity values of different cell types, calculated using the single-shell model. Low conductivity buffers are used for trapping experiments. These low conductivity buffers help reduce the Joule heating. Viability of the cells in the buffer system was studied in detail with a population size of approximately 100 cells for each study. The work also demonstrates the development of the parallelized single cell trap device with optimized traps. This device is also capable of being coupled detection of target protein using MALDI-MS.
ContributorsBhattacharya, Sanchari (Author) / Ros, Alexandra (Committee member) / Ros, Robert (Committee member) / Buttry, Daniel (Committee member) / Arizona State University (Publisher)
Created2013
Description
Polydimethyl siloxane is a commonly used fabrication material for microfluidic devices. However, its hydrophobic nature and protein adsorption on the surface restricts its use for microfluidic applications. Also, it is critical to control the electroosmotic flow for electrophoretic and dielectrophoretic manipulations. Therefore, surface modification of PDMS is essential to make it well suited for bioanalytical applications. In this project, the role of polyethylene oxide copolymers F108 and PLL-PEG has been investigated to modify the surface properties of PDMS using physisorption method. Measuring electroosmotic flow and adsorption studies tested the quality and the long-term stability of the modified PDMS surface. Static and dynamic coating strategies were used to modify the PDMS surface. In static coating, the PDMS surface was incubated with the coating agent prior to the measurements. For dynamic coating, the coating agent was always present in the solution throughout the experiment. F108 and PLL-PEG were equally effective to prevent the protein adsorption under both strategies. However, dynamic coating was more time saving. Furthermore, effective reduction of EOF was observed with F108 coating agent under dynamic conditions and with PLL-PEG coating agent under static conditions. Moreover, PLL-PEG dynamic coatings exhibited reversal of EOF. These important findings could be used to manipulate EOF and suggest optimal coating agent and strategies for PDMS surface treatment by the physisorption method.
ContributorsManchanda, Shikha (Author) / Ros, Alexandra (Thesis advisor) / Hayes, Mark (Committee member) / Liu, Yan (Committee member) / Arizona State University (Publisher)
Created2012
DescriptionThis project largely focuses on the Latino population and how Hispanic parents should become more involved with their student's education in order to have them prosper in today's society.
ContributorsSanchez Ruiz, Dorian Nazaret (Author) / Walters, Molina (Thesis director) / Oliver, Jill (Committee member) / Barrett, The Honors College (Contributor) / School of Politics and Global Studies (Contributor) / School of International Letters and Cultures (Contributor)
Created2014-05
Description
This project covered different components to strengthen Model United Nations organizations, especially programs in Arizona itself. The lack of strong programs in Arizona can be attributed in many ways to a lack of resources, and this project's work aims to bolster programs by providing some resources. The written component contains a write-up of a 2013 High School Model United Nations Conference at Arizona State University; a write-up of a 2014 Middle School Model United Nations Conference at Arizona State University; a guide on how to run such a conference, focused at the high school level; a university-level curriculum that integrates a Model United Nations organization into a classroom setting, including assignments and; a grade school lesson plan with seven lessons that focuses on teaches students about international relations and global affairs while preparing them for a Model United Nations conference.
ContributorsLanza, Jentry Elizabeth (Author) / Von Hagen, Mark (Thesis director) / Hutchinson, Marcie (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Politics and Global Studies (Contributor) / School of Historical, Philosophical and Religious Studies (Contributor)
Created2014-05
Description
There is a serious need for early childhood intervention practices for children who are living at or below the poverty line. Since 1965 Head Start has provided a federally funded, free preschool program for children in this population. The City of Phoenix Head Start program consists of nine delegate agencies, seven of which reside in school districts. These agencies are currently not conducting local longitudinal evaluations of their preschool graduates. The purpose of this study was to recommend initial steps the City of Phoenix grantee and the delegate agencies can take to begin a longitudinal evaluation process of their Head Start programs. Seven City of Phoenix Head Start agency directors were interviewed. These interviews provided information about the attitudes of the directors when considering longitudinal evaluations and how Head Start already evaluates their programs through internal assessments. The researcher also took notes on the Third Grade Follow-Up to the Head Start Executive Summary in order to make recommendations to the City of Phoenix Head Start programs about the best practices for longitudinal student evaluations.
ContributorsArmfield, Jessica Ann (Author) / Duggan, Mary Anne (Thesis director) / Dumka, Larry (Committee member) / Barrett, The Honors College (Contributor) / T. Denny Sanford School of Social and Family Dynamics (Contributor) / School of International Letters and Cultures (Contributor)
Created2014-05
Description
Through interviews with student participants in Barrett Summer Scholars during 2012, I uncovered how education in Arizona is failing and succeeding in meeting the needs of its high-achieving, oftentimes academically disillusioned students. Many high-achieving students feel underserved by their education and do not receive adequate challenges or one-on-one attention. Socioeconomic, ethnic, and racial limitations further contribute to the disenchantment of students and educational inequalities in the US and Arizona in particular. The Barrett Summer Scholars program itself intends to help engage these students, but it may be failing in its stated goals. Limited resources make it difficult for schools to pay as much attention to the high-achieving students as to the low-achieving, but Barrett might be able to help bridge this gap and provide students with one-on-one attention by way of student mentorship.
ContributorsManrique, Liliana (Author) / Popova, Laura (Thesis director) / Eder, James (Committee member) / Barrett, The Honors College (Contributor) / School of International Letters and Cultures (Contributor) / School of Human Evolution and Social Change (Contributor)
Created2014-05
Description
As we count down the years remaining before a global climate catastrophe, ever increases the importance of teaching environmental history and fostering environmental stewardship from a young age. In the age of globalization, nothing exists in a vacuum, yet our traditional education system often fails to reflect the abundant connections between content areas that are prevalent outside of schools. In fact, many of the flaws of the field of education have been exacerbated by the COVID-19 pandemic and a forced transition to online schooling, with many educators reverting to outdated practices in a desperate attempt to get students through the year. The aim of this project was to design a unit curriculum with these issues in mind. This month-long environmental history unit engages students through the use of hands-on activities and promotes interdisciplinary connections. The unit can be taught in a physical, online, or hybrid American history class, and will hopefully inspire and motivate students to become environmental stewards as they look toward their futures on this planet.
ContributorsColeman, Lauren Jean (Author) / Walters, Molina (Thesis director) / Anthony, Charles (Committee member) / School of International Letters and Cultures (Contributor) / School of Mathematical and Statistical Sciences (Contributor) / Division of Teacher Preparation (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2021-05